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SubjectRe: Yet more softlockups.
On 7/12/13 11:18 AM, Dave Jones wrote:
> On Fri, Jul 12, 2013 at 11:12:13AM -0600, David Ahern wrote:
> > On 7/12/13 9:45 AM, Dave Jones wrote:
> > > Here's a fun trick:
> > >
> > > trinity -c perf_event_open -C4 -q -l off
> > >
> > > Within about a minute, that brings any of my boxes to its knees.
> > > The softlockup detector starts going nuts, and then the box wedges solid.
> >
> > I tried that in a VM running latest Linus tree. I see trinity children
> > getting nuked regularly from oom.
>
> Weird. I'm curious what the backtrace looks like in those cases.
> Where is it trying to allocate memory ?
> (Though that isn't usually too helpful in most cases, but in absense of
> anything else..)

(gdb) bt
#0 0x000000313b27f3e0 in malloc () from /lib64/libc.so.6
#1 0x0000000000404405 in _get_address
(null_allowed=null_allowed@entry=1 '\001') at generic-sanitise.c:151
#2 0x00000000004044ca in get_address () at generic-sanitise.c:182
#3 0x00000000004052a0 in fill_arg (childno=<optimized out>,
call=call@entry=298, argnum=argnum@entry=1) at generic-sanitise.c:415
#4 0x000000000040548d in generic_sanitise (childno=childno@entry=0) at
generic-sanitise.c:615
#5 0x0000000000405620 in mkcall (childno=childno@entry=0) at syscall.c:131
#6 0x0000000000407d85 in child_process () at child.c:219
#7 0x00000000004073ad in fork_children () at main.c:103
#8 main_loop () at main.c:308
#9 do_main_loop () at main.c:342
#10 0x000000000040253a in main (argc=<optimized out>, argv=<optimized
out>) at trinity.c:180


In _get_address, case 8 must be happening a lot and I don't see a free
when that address comes from malloc. Perhaps all of the rand() calls are
breaking down in the VM. If I change that case from malloc to something
static - like page_rand - memory stays flat.

David


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